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Abstract:

A method for use in a cellular system with a controlling node and user
terminals, UEs. In the system, UEs can assume one of at least two states,
a non-listening state, i.e. a state during which a UE does not listen for
data from its controlling node, and a listening state, an "on duration"
state. According to the method a UE in the system is able to alternate
between said two states according to a certain scheme, the scheme
according to which a UE in the system alternates between said two states
being dependent on whether or not data units which are transmitted
between the UE and its controlling node are received entirely and
correctly within an initially allocated resource for each data unit.

Claims:

1. A method for use in a cellular wireless access system, in which system
there is a first controlling node which controls transmissions to and
from user terminals (UEs) within a certain area, and in which system UEs
assume one of at least two states, the at least two states including a
first non-listening state wherein a UE does not listen for data from its
controlling node, and a second listening state, the method comprising: a
UE alternating between the two states in dependence on whether or not
data units which are transmitted between the UE and the controlling node
are received entirely and correctly within an initially allocated
resource for each data unit, as allocated by the controlling node.

2. The method of claim 1 wherein alternating between the two states is
configured to accommodate HARQ ACK/NACK transmissions between the UE and
its controlling node.

3. The method of claim 1 wherein alternating between the two states is
configured to accommodate RLC segmentation between the UE and its
controlling node.

4. The method of claim 1 wherein the initially allocated resource is
chosen from one of the following: a resource in time; a resource in
frequency; and a Modulation and Coding Scheme.

5. The method of claim 1 wherein the alternating includes scheduling
occasions at which the UE goes from the non-listening state to the
listening state to correspond to expected first transmissions of data
from the controlling node.

6. The method of claim 5 wherein as a further aspect of the alternating:
if no data has been received by the UE during a listening period, the UE
enters the non-listening state immediately; and if data has been received
during the listening period, the UE remains in the listening state until:
the UE has transmitted the corresponding ACK/NACK; and, if a NACK is
transmitted, until the corresponding retransmission is expected, or, if
the received data comprises an RLC PDU (Protocol Data Unit) segment,
until all the data has been received.

7. The method of claim 1 wherein as part of the alternating, for
transmissions from the controlling node to the UE, after the UE has
transmitted a data unit to the controlling node, the UE waits for the
ACK/NACK from the controlling node before changing from the listening
state to the non-listening state, and if a NACK is received, the UE
remains in or transitions to the listening state for the time when the
retransmission from the controlling node is expected.

8. The method of claim 1: wherein the cellular wireless access system
comprises an LTE system; and wherein the first, non-listening state is
the DRX state; wherein the controlling node is an eNodeB.

9. A transceiver for use as a User Terminal (UE) in a cellular wireless
access system, in which system there is a first controlling node which
controls transmissions to and from the UE, the UE comprising: transceiver
circuits for sending data to the controlling node and receiving data from
the controlling node; a control circuit configured to alternate the UE
between at least two states, the at least two states including a first
non-listening state where the UE does not listen for data from the
controlling node, and a second listening state; wherein the control
circuit is configured to alternate the UE between the two states in
dependence on whether or not data units which are transmitted between the
UE and the controlling node are received entirely and correctly within an
initially allocated resource for each data unit, as allocated by the
controlling node.

10. The UE of claim 9 wherein the control circuit is configured to adapt
its alternating between the two states to accommodate HARQ ACK/NACK
transmissions between the UE and the controlling node.

11. The UE of claim 9 wherein the control circuit is configured to adapt
its alternating between the two states to accommodate RLC segmentation
between the UE and the controlling node.

12. The UE of claim 9 in which the initially allocated resource comprises
one of the following: a resource in time; a resource in frequency; and a
Modulation and Coding Scheme.

13. The UE of claim 9 wherein, for transmissions from the controlling
node to the UE, the control circuit is configured to schedule the
occasions when the UE goes from the non-listening state to the listening
state to correspond to expected first transmissions of data from the
controlling node.

14. The UE of claim 13 wherein the control circuit is configured to: make
the UE enter the non-listening state from the listening state, if no data
was received during an on-duration of a listening period; make the UE
remain in the listening state, if data was received during the listening
period, until: the UE has transmitted the corresponding ACK/NACK; and, if
a NACK is transmitted, until the corresponding retransmission is
expected; or, if the received data comprises an RLC PDU (Protocol Data
Unit) segment, until all the data has been received.

15. The UE of any claim 9 wherein, for transmissions from the UE to the
controlling node, after the UE has transmitted a data unit to the
controlling node, the control circuit is configured to make the UE wait
for the ACK/NACK from the controlling node before assuming the
non-listening state, and, if a NACK is received, to maintain the UE in
the listening state, or to change the UE to the listening state, for the
time when the retransmission from the controlling node is expected.

16. The UE of claim 9: wherein the UE is configured for use in an LTE
system; wherein the first, non-listening state is the DRX state; wherein
the controlling node is an eNodeB.

Description:

RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent application Ser.
No. 12/596,782, having a §371 entry date of Oct. 20, 2009, which is
a U.S. national stage application of PCT/SE2007/050882, filed Nov. 21,
2007, which claims the benefit of Swedish Patent Application Serial No.
0701030-9 filed Apr. 27, 2007, the disclosures of each of which are
incorporated herein by reference in their entirety.

TECHNICAL FIELD

[0002] The present invention discloses a method and a device for saving
power in a user terminal in a cellular wireless access system of the 3G
kind.

BACKGROUND

[0003] In the Third Generation Partnership Project (the 3GPP project) for
cellular wireless systems, a mechanism referred to as Discontinuous
Reception (DRX) will be introduced. One purpose of DRX is to save battery
time in user terminals.

[0004] By means of the DRX mechanism, a user terminal will be able to turn
on and off radio resources for a certain amount of time, based on
configured parameters and specified rules.

[0005] As an example of a DRX mechanism, mention might be made of the so
called Continuous Packet Connectivity mechanism, CPC, for WCDMA systems,
in which a DRX scheme is specified. According to this scheme, a user
terminal initiates continuous usage of its radio resources (continuous
reception) as soon as it receives data during a non-DRX period, and
resumes a DRX state based on a "timeout" following a period in time
during which no data is received.

[0006] In 3G (third generation) systems, as in many other wireless
cellular systems, there is a controlling node, in 3G referred to as
eNodeB, which has as one of its purposes to control traffic to and from
user terminals within a certain area, a cell, in the system. In order for
a DRX mechanism to function properly, a set of clear rules are needed to
enable the eNodeBs of the system to determine, at all times, the state of
"their" user terminals with respect to DRX, i.e. DRX or not.

[0007] In 3G systems, the solutions currently envisioned for DRX schemes
don't properly take into account the fact that different kinds of
transmissions or retransmissions may be used between the eNodeBs and
their respective UEs. Examples of such different kinds of (re-)
transmissions are transmissions which are caused by the use of HARQ,
Hybrid Automated Repeated Request, and those which are caused by the use
of Radio Link Control, RLC.

[0008] Current solutions for DRX schemes assume either: [0009] that only
one transmission is needed, or [0010] that if one or more retransmissions
and/or if multiple RLC segments are needed, those are handled by the DRX
scheme as first transmissions, or [0011] that once data is received, the
UE will listen for an "on duration" period of time, regardless of whether
or not retransmissions or new data is expected of not, which means that
the radio resources will always be committed for a longer period than the
actual need for listening, as the UE goes on listening until it assumes
the DRX state, which is done after the expiration of a configured
inactivity timer.

[0012] Generally, a packet can be transmitted using dynamic scheduling, by
means of which explicit signalling is used by the eNodeB to notify the UE
that data is coming, or using semi-persistent scheduling, in which the
first transmission from the eNodeB is detected by the UE using so called
"blind detection", and retransmissions from the eNodeB are made using
scheduling assignments, as with dynamic scheduling.

[0013] In HARQ transmissions, for downlink transmissions, the UE sends a
HARQ NACK to its eNodeB to request a retransmission. The eNodeB does not
have advance knowledge that a retransmission will be needed, and can thus
not signal in advance using MAC signalling to order the UE to assume a
shorter DRX period to allow for retransmissions. A retransmission can
occur after a certain amount of time, typically measured in milliseconds,
during which time no resources will be used for this transmission.

[0014] In addition, with semi-persistent scheduling, which is likely to be
used for VoIP, retransmissions are made using scheduling assignments just
as with dynamic scheduling. The general problem that the retransmission
will be delayed by the length of the DRX period is thus independent of
the type of service or transmission.

SUMMARY

[0015] As explained above, there is thus a need for a solution by means of
which a cellular wireless access system of the 3G kind, in particular the
system known as Long Term Evolution, LTE, could overcome the problems
posed by the combination of DRX intervals and different kinds of multiple
transmissions, such as those caused by e.g. HARQ ACK/NACK and RLC
segmentation.

[0016] The solution should also be possible to apply in other kinds of
systems than LTE systems, in which there are periods similar to the DRX
periods, i.e. periods during which a UE does not listen for data from its
controlling node.

[0017] Such a solution is offered by the present invention in that it
discloses a method for use in a cellular wireless access system, in which
system there can be a first controlling node which serves, inter alia, to
control transmissions to and from user terminals, UEs, within a certain
area, such as a cell.

[0018] In the system in which the invention is applied UEs can assume one
of at least two states, a first such state being a non-listening state,
i.e. a state during which the UE does not listen for data from its
controlling node, and a second such state being a listening state, i.e.
an "on duration" state.

[0019] A UE in the system is able to alternate between said two states
according to a certain scheme, said scheme depending on whether or not
data units which are transmitted between the UE and its eNodeB are
received entirely and correctly within an initially allocated resource
for each data unit, said allocation having been carried out by the
controlling node.

[0020] If the method of the invention is applied to a system of the LTE
kind, the first non-listening state will be the DRX state, and the
controlling node will be an eNodeB.

[0021] Thus, the invention offers a solution by means of which the demands
posed on the DRX function or similar functions by differing kinds of
retransmissions (HARQ ACK/NACK and RLC segmentation) can be addressed.

[0022] This and other advantages of the present invention will become even
more apparent from the following detailed description.

[0023] In addition, the invention also discloses a transceiver for use as
a user terminal in a system in which the method of the invention is
applied.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 shows a schematic overview of a system in which the
invention may be applied.

[0025]FIG. 2 shows a diagram with some of the definitions used in this
text.

[0026] FIG. 3 shows a flow chart of a method of the invention.

[0027] FIG. 4 shows a block diagram of a transceiver of the invention.

DETAILED DESCRIPTION

[0028]FIG. 1 shows a rough overview of a system in which the invention
can be applied. As has been mentioned previously, the system for which
the invention is intended is a wireless cellular access system of the LTE
kind (Long Term Evolution). Such a system will, as shown in FIG. 1,
comprise a controlling node 110, which has as one of its roles to control
all the traffic to and from user terminals, UEs, within a certain area, a
so called cell within the system. On such cell is shown symbolically as
120 in FIG. 1, with one UE 130 within the cell.

[0029] Naturally, the number of cells in a system in which the invention
is applied, and the number of UEs which can be used within such a cell
can be varied greatly, the number of cells and UEs shown in FIG. 1 is
merely an example intended to facilitate the reader's understanding of
the present invention.

[0030] In addition, the type of system in which the invention is applied
need not be an LTE type of system, the invention can be applied in other
types of wireless cellular access systems as well. Thus, the use of
terminology in this description of terms borrowed from LTE type systems
should merely be seen as examples intended to facilitate the reader's
understanding of the present invention.

[0031] As also explained previously, the invention mainly deals with
problems posed by mechanisms involving periods of discontinuous
reception, in LTE referred to as so called DRX periods. Before the
invention is described in more detail, some basic definitions used in
this text will first be explained, with reference to FIG. 2.

[0032]FIG. 2 shows the UE radio state as a function of time, the time
being shown in TTIs, Transmission Time Intervals. The numerals used in
FIG. 2 correspond to the following definitions or events:

[0033] 1. Wake up points, points in time at which a UE wakes up, or in
other words goes from a DRX state to a listening state.

[0034] 2. Implicit go to sleep order: if the UE does not receive any data
during the on duration period, it assumes the DRX state.

[0035] 3. Implicit Stay awake order: if the UE receives any Best Effort
data during an on duration period it extends the current on duration
period by a certain pre-determined amount of time, suitably the length of
one more on duration periods.

[0036] 4. DRX intervals, intervals with which a certain DRX pattern is
repeated.

[0037] 5. On-duration period: a period in time during which the UE waits
for the reception of data, after waking up from DRX.

[0038] 6. Inactivity timer: a duration in time that the UE waits to
successfully receive data (decode PDCCH) from the last reception of data
(decoding of PDCCH), failing which the UE re-enters the DRX state, i.e.
the non-listening state. The UE restarts the activity timer following a
single reception of data (decoding of a PDCCH).

[0039] 7. One TTI, Transmission Time Interval.

[0040] 8. "Awake" time for the UE.

[0041] 9. Explicit stay awake: an eNodeB may send an explicit order to a
UE to stay awake, usually by means of so called MAC signalling.

[0042] 10. Explicit go to sleep: an eNodeB may send an explicit order to a
UE to go to sleep, usually by means of so called MAC signalling.

[0043] In addition to the periods and events shown in FIG. 2, there also
exists the notion of a "DRX period", i.e. a period during which the UE
assumes an idle state, i.e. it does not listen for data during this
period. This period may be variable, and normally equals the DRX interval
minus the awake time during the DRX interval.

[0044] Returning now to the present invention, the invention is, as has
been mentioned previously, intended to address problems with the DRX
state, and different kinds of transmissions, such as transmissions which
use HARQ and RLC, mainly problems involving retransmissions (HARQ) and
transmissions in more than one TTI (mainly RLC).

[0045] The invention proposes to address these problems by means of taking
into account the following: [0046] the original transmissions, [0047] N
possible additional transmissions, in consecutive TTIs (RLC segmentation,
although the invention does not necessarily rely on the segments being in
consecutive TTIs, but could also work, for example, in conjunction with a
scheduler that could prioritize the sending of RLC segments), [0048] N
possible additional transmissions, in non-consecutive TTIs (e.g. HARQ
retransmissions or RLC segments).

[0049] Very basically, the invention proposes a solution in which the DRX
scheme is bound to the type of transmission, so that one DRX scheme can
be used for transmissions that employ HARQ-like principles, and another
DRX scheme may be used for transmissions that employ RLC principles.

[0050] In the following, two different embodiments of the invention will
be described, one which is adapted to HARQ-principles, and another one
which is adapted to RLC principles.

FIRST EMBODIMENT

HARQ Principles

[0051] In this embodiment, the DRX scheme is configured without
considering HARQ retransmissions, i.e. the wake up occasions correspond
to the expected first transmissions.

[0052] For downlink transmission, i.e. for transmissions from the eNodeB
to the UE, if no data is received during a configured wake-up period, the
UE immediately enters the DRX state again until the next configured
wake-up period. If a transmission has been received, the UE stays awake
at least:

[0053] a) when it transmits the HARQ ACK/NACK;

[0054] b) and, if a NACK is transmitted, when the retransmission is
expected.

[0055] This can be done outside of the DRX pattern, i.e. the UE is awake
at the known occasions a) and b) until it has transmitted a HARQ ACK and
no further retransmissions are expected. The UE can also optionally go to
sleep between occasions a) and b).

[0056] When HARQ principles are employed by the system, a case can be
envisioned in which the UE transmits a HARQ ACK but the eNodeB misreads
this as a HARQ NACK. In such a case, i.e. misreading of ACK as NACK, if
the UE is in the DRX state right after sending the HARQ ACK, the
retransmission from the eNodeB, and any subsequent retransmission
attempts, will be lost. This will lead to the maximum number of
retransmissions being performed by the eNodeB even if the UE received the
data in the first attempt.

[0057] In order to cover this case, i.e. the case where the UE transmits a
HARQ ACK but the eNodeB misreads this as a HARQ NACK, the following
functionality can be added to the method of the invention:

[0058] To address this error case, the UE can extend its stay in the on
duration state by a predefined period of time, or until it is clear to
the UE that no retransmissions are attempted by the eNodeB, i.e. the UE
does not receive any retransmission from the eNodeB during the time a
retransmission would have been performed if a transmitted ACK had been
misread as a NACK. This will thus reduce the risk of the eNodeB reaching
the maximum number of retransmissions.

[0059] Tying the resumption of the DRX state to the HARQ, as suggested
above, has as an additional benefit in that it achieves the same result
as an explicit "go to sleep request" to the UE from the eNodeB after a
successful reception/transmission. Thus, the eNodeB will know that the UE
is in the DRX state or not.

[0060] For uplink transmissions, i.e. transmissions from the UE to the
eNodeB, a similar behavior as that suggested above for the downlink can
be applied: After the UE has transmitted a data unit to the eNodeB, it
does not immediately assume the DRX state. Instead, it waits for the HARQ
ACK/NACK from the eNodeB, i.e. the UE must "be awake" at least when the
ACK/NACK is expected. If a NACK is received, the UE must also be awake
when the retransmission is performed, similarly to that which has been
described above for the downlink.

[0061] It should be pointed out that "waking up" above includes the case
when "blind detection" is used (even for retransmissions), i.e. the case
where a UE instead of waking up only for one specific TTI would instead
listen for data during a small interval.

SECOND EMBODIMENT

RLC Segmentation

[0062] This is an embodiment which is particularly suitable for DRX in
combination with RLC segments/RLC segmentation.

[0063] In this embodiment, the DRX scheme is configured without
considering any possible use of RLC segmentation, i.e. the wake up
occasions correspond to the expected first transmissions.

[0064] For downlink transmissions, i.e. from the eNodeB to the UE, if no
data is received during a configured wake-up period, the UE will
immediately enter the DRX state and remain there until the next
configured wake-up period. If a transmission has been received, the UE
stays awake at least:

[0065] a) if it detects that the data received contains an RLC PDU
(Protocol Data Unit) segment; and

[0066] b) until all RLC segments are properly received. Either the UE can
stay awake to receive all such segments, or the UE will "know" that in
similarity to HARQ retransmission, the next RLC segment(s) will not come
until a certain amount of TTIs have passed. If the UE sends a NACK, it
can "sleep" as per the HARQ principles explained above, although it must
wake up if a segment is expected during that time. One aspect of this is
that the RLC segments won't trigger a new on-duration period, and in
particular, when the last segment is received, the UE can enter the DRX
state.

[0067] The "awake times" described immediately above can be kept outside
of the ordinary DRX pattern, i.e. the UE will be awake at known occasions
a) and b) until it has transmitted a HARQ ACK for all RLC segments and no
further RLC segments are expected.

[0068] Tying the wake-up time of the UE with the detection of RLC segments
in this way has the additional benefit of achieving the same as an
explicit "on duration" or "go to continuous level request" from the
eNodeB when sending a data unit over several TTIs (which are possibly,
but not necessarily consecutive) and also the same effect as an explicit
"go to sleep request", i.e. "enter DRX" from the eNodeB to the UE after
successful reception/transmission.

[0069] For uplink transmissions, i.e. from the UE to the eNodeB, a similar
pattern can be applied. After the UE has transmitted a segmented data
unit, it will not immediately go to sleep, but will instead continue
sending all RLC segments, i.e. the UE must be awake at least until all
segments are sent and until they are acknowledged.

[0070] FIG. 3 is a flow chart of some steps of a method 300 of the
invention. Steps which are options or alternatives have been indicated
with dashed lines. Thus, as indicated in FIG. 3, according to the method
300, a UE in the system in which the invention is applied is able to
alternate, step (310, between the two states mentioned previously in this
text according to a certain scheme, with this scheme being dependent on
whether or not data units which are transmitted between the UE and its
controlling node are received entirely and correctly within an initially
allocated resource for each data unit, as shown in step 320.

[0071] Step 330 shows that according to the method of the invention, the
scheme for altering between the two states can in one embodiment be
adapted to accommodate HARQ ACK/NACK transmissions between the UE and its
controlling node. As shown in step 340, in one embodiment of the method
300, the scheme for altering between the two states can also be adapted
to accommodate RLC segmentation between the UE and its controlling node.

[0072] Step 350 of FIG. 3 shows that, in another embodiment of the method
300, for transmissions from the controlling node to the UE, i.e. down
link, "DL", the occasions when the UE goes from the non-listening state
to the listening state can be scheduled to correspond to expected first
transmissions of data from the controlling node.

[0073] Step 360 shows that a UE can remain in the listening state
("non-DRX") until: [0074] the UE has transmitted the corresponding
ACK/NACK; and [0075] if a NACK is transmitted, until the corresponding
retransmission is expected, and [0076] if the received data comprises an
RLC PDU segment, until all the data has been received.

[0077] As indicated in step 370, if the UE transmits an ACK, the UE
extends its stay in the listening state by a predefined period of time,
to ensure that the UE does not receive any retransmission ("Re-TX") from
the controlling node during the time that a retransmission would have
been performed if an ACK transmitted by the UE had been misread by the
controlling node as a NACK.

[0078] Step 380 shows that for transmissions from the UE to the
controlling node, after the UE has transmitted a data unit to the
controlling node, the UE waits for the ACK/NACK from the controlling node
before assuming the non-listening state, and if a NACK is received, the
UE is in the listening state when the retransmission is expected.

[0079] FIG. 4 shows a rough block diagram of a transceiver 400 of the
invention, for use as a UE which basically functions as described above.
As can be seen in FIG. 4, the UE 400 of the invention comprises an
antenna 410 for communicating with the eNodeB, and also comprises a
transmitter 430 and a receiver 420. In addition, the UE 400 also
comprises control means such as for example a microprocessor 440, as well
as comprising a memory 450.

[0080] The transceiver 400 basically comprises means for functioning
according to the method described above, and thus comprises means such as
the controller 440 and the memory 450 for assuming one of at least two
different states, a first such state being an idle state, a DRX state,
and a second such state being a listening state, an "on duration" state,
each state being assumed for a certain amount of time. Suitably, the
controller 440 controls the length of time for the DRX and non-DRX
periods, which it can retrieve from the memory 450.

[0081] It should be noted that although the controller 440 and the memory
are depicted here as being part of the alternating mechanism, the antenna
410 and the receiver 420 may also be a part of this mechanism, if, for
example, the eNodeB transmits information or commands relevant to the
alternating.

[0082] However, the alternating means, in this case the means 440, 450,
make the scheme according to which the UE alternates between said two
states dependent on whether or not data units which are transmitted
between the UE and its controlling node are received entirely and
correctly within an initially allocated resource for each data unit.

[0083] In the UE 400 of the invention, the alternating means 440, 450, may
also adapt the scheme for altering between the two states to accommodate
HARQ ACK/NACK transmissions between the UE 400 and its controlling node,
e.g. the eNodeB. Alternatively, the alternating means 440, 450, may adapt
the scheme for altering between the two states to accommodate RLC
segmentation between the UE 400 and its controlling node 110.

[0084] In one embodiment of the UE 400, the above mentioned initially
allocated resource is one of the following: [0085] a resource in time,
e.g. a TTI [0086] a resource in frequency, e.g. a sub-frame or a resource
block [0087] a Modulation and Coding Scheme, i.e. a modulation, a code
rate and a number of transmission bits.

[0088] In a further embodiment of the UE 400, in the case of transmissions
from the controlling node to the UE, the alternating means 400, 450,
schedule the occasions when the UE goes from the non-listening state to
the listening state to correspond to expected first transmissions of data
from the controlling node.

[0089] Also, if no data has been received by the UE during a listening
period, the alternating means 440, 450, may make the UE enter the
non-listening state immediately, and if data has been received, the
alternating means 440, 450, can make the UE remain in the listening state
until: [0090] the UE has transmitted the corresponding ACK/NACK: and
[0091] if a NACK is transmitted, until the corresponding retransmission
is expected, and [0092] if the received data comprises an RLC PDU
segment, until all the data has been received.

[0093] Additionally, if the UE transmits an ACK, the alternating means
440, 450, may make the UE extend its stay in the listening state by a
predefined period of time, in order to ensure that the UE does not
receive any retransmission from the controlling node during the time that
a retransmission would have been performed if an ACK transmitted by the
UE had been misread by the controlling node as a NACK.

[0094] In another embodiment of the invention, for Uplink, UL,
transmissions, after the UE has transmitted a data unit to the
controlling node, the alternating means 440, 450, make the UE wait for
the ACK/NACK from the controlling node before assuming the non-listening
state, and if a NACK is received, the UE is kept in the listening state
when the retransmission from the controlling node is expected.

[0095] The invention is not limited to the examples of embodiments
described above and shown in the drawings, but may be freely varied
within the scope of the appended claims. For example, although the
invention has mainly been described above with terms from systems of the
LTE kind, the invention may be applied to other kinds of wireless
cellular access systems.

[0096] Also, in a slightly different aspect of the invention, the
following principles may be applied: [0097] For HARQ and RLC segments a
specific a DRX scheme is used, which scheme is independent of the "main"
DRX scheme, and which has the following principles: [0098] for HARQ and
RLC segmentation [0099] the UE is allowed to sleep in-between
transmissions subsequent to the initial transmission; the time the UE
sleeps may be X TTIs, where X is configured by eNodeB to the UE using
e.g. RRC signalling (for asynchronous HARQ and for RLC segments) or a
predefined value based on physical layer property (for synchronous HARQ
e.g. LTE uplink). After X TTIs, the UE wakes up, and listens until the
transmission is received. [0100] the UE stays awake until all subsequent
transmissions belonging to the initial transmissions have completed,
either HARQ or RLC, or both. [0101] In both cases, the UE can go back
to the DRX state as soon as the transmission after which it may resume
sleeping is received. Obviously, the UE may not assume the DRX state if
the "main" DRX scheme would not allow it otherwise.

Patent applications by Ghyslain Pelletier, Laval CA

Patent applications by Johan Torsner, Masaby FI

Patent applications by Jonas Pettersson, Lulea SE

Patent applications by Kristofer Sandlund, Lulea SE

Patent applications by TELEFONAKTIEBOLAGET L M ERICSSON (PUBL)

Patent applications in class Signaling for performing battery saving

Patent applications in all subclasses Signaling for performing battery saving